Method and apparatus for making granular coated webs



Dec. 27, 1938. I R. MELTON ET AL 1,

METHOD AND APPARATUS FOR MAKING GRANULAR COATED WEBS Original Filed Dec. 14, 1952 3 Sheets-Sheet 1 4 INVENTORS ROME L.MELTON RAYMOND o. BENNER y HENRY P. KIRGHNER ATTORNEY Dec. 27 193s.

R. L. MELTON 1- AL 2,141,658

METHOD AND APPARATUS FOR MAKING GRANULAR- COATED WEBS Original Filed Dec. 14, 1932 s Sheets-Sheet 2 INVENTORS ROMIE L.MELTON RAYMOND G.BENNER- BY HENRY K\RGHNER A TTORNEY A 27 193 8; R. AMELTON ET AL v ,1 5

METHOD AND APPARATUS FOR MAKING GRANULAR COATED WEBS Origipal Filed Dec. 14, 1932 3 SheetsSh e et 3 I INVENTORS ROMIE L. MELTON RAYMOND C. BENN ER BY HE NRY A TTORNEY K RGHNER Patented Dec.

METHOD AND APPARATUS FOR MAKING GRANULAR COATED WEBS Romie L. Melton, Raymond C. Benner, and Henry P. Kirchner, Niagara Falls, N. Y., assignors, by mesne assignments, to The Carborundum Company, Niagara Falls, N. Y.; a corporation of Delaware Application December 1 4, 1932, Serial N0. 641,241

Renewed August 11, 1937 BOlaims.

This invention relates to the manufacture of granular coated webs of such material as paper. cloth, and the like, and-has for an object the provision of apparatus and a method for the manufacture of superior articles.

Granular coated webs, of which abrasive coated paper and abrasive coated cloth are examples,

. face coating of a suitable adhesive.

have been made in the past by dropping the ,granular. materials onto a web of paper or cloth,

as the case may be, upon which there was a sur- The operation of coating the web with granular materials was carried out with the adhesive side of the web facing upward in order that the grain might be deposited by gravitational attraction.

The result of the method previously used hasbeen that, because of the gravitational attraction upon the grains, thegranular coating on the web did not present as sharp a surface .as could be desired. The arrangement of the particles on the web has been haphazard but with all grains having flat surfaces and all grains of splintery .shape lying flat on the surface of the adhesive *coated web. The result of such flatwise' deposition of the grain on the adhesive coated web has" been that the granular particles did not present their sharpestedgesor surfaces to the material being abraded, but instead, they presented their less sharp and frequently actually blunt edges to the material. e

We have found that a superior productcan be made by depositing the grains upon the ad-' that used heretofore. In practicing one modification of our invention, we support the adhesive coated webin an inverted position or, in other words, with the adhesive coated side downward and then project thegrains upward to this adhesive coated surface.

be made to strike the adhesive coated web endwise instead of 'flatwise and that the inverted position of the adhesive coated web, because of the effect of gravity upon the particles, will maintain the endwise attachment of the particles and also will tend to cause all particles to assume'the same general relationship with respect to the surface of the'web. In this manner it is possible to so position the grains on the adhesive coated web I that the major axes of a substantial proportion of the granules are normal with respect to the web or sothat asubstantial proportion of the gran- Q iules have their major axes at an oblique angle with respect to the web. By so-positioning the web holding means and the grain projecting hesive coatedweb in a manner different from We have found that by coating the web in this manner. the granufes-can me'ans relatively to each other that the grains are directed perpendicularly toward the web, a substantial proportion of the grains are oriented normal to the web. on the other hand, if the relativepositions of the web holding means and the grain projector are such that the particles are directed at an oblique angle toward the web, a substantial proportion of the grains; become oriented at an oblique angle with respect to the web." Whether the particles are normal with respect to the web or at an oblique angle with respect to the web or some are normal and others oblique, the result is an abrasive coated web that is sharper than that previously known and made by gravity deposition of the grains upon an upwardly facing adhesive coated surface.

The character of the granular coated surface obtained by carrying out the above modification of our invention can be best described in a brief way by calling it a. serrated surface and this term shah be understood to mean, wherever it is used in this specification, a surface in which the granular particles, arevso positioned that a substantial proportion of them project from the surface of the web instead of lying flat upon the web as has. been the case with the articles previously known. As. a matter of convenience in expressing the different degrees of sharpness of the granular coating, we make use of the term index of serration", and wish tohave it understood that wherever that term is used inthis specification it means the percentage relationship of the number of projecting grains to the total number of grains, as determined by microscopic count. I

We have found that the index of serration of granular coated webs made by our method is greater t n per cent and frequently is between percent and per cent, whereas the index of serration of the, previously known granular coated webs is less'than 40 per cent.-

-A better understanding of the nature of a serrated surface and its contrast with the granular coated surfaces previously known, as well as methods and apparatus for the producti'on of such serrated surfaces, can be secured by reference to the accompanying drawings in which:

Figure 1 illustrates a side elevation of the previously known-granular coated webs;

Figure 2 shows a serrated surface in which the granules are attached endwise to the web;

Figure 3 shows the manner in which oriented grain engages with the material being abraded; Figure 4 shows, in schematic view, appara for'producing a serrated surface; a

' Figures 5 and 6 show modifications of grain projectors suitable for carrying out our invention; and

Figures '7 and 8 show modifications of the projecting means shown in Figure 4.

In Figures 1, .2 and 3, the grains l are shown to be held to the web P by means of the adhesive 3. It will be noted from these drawings that 'a sharp contrast exists between the grains as they It will be noted when the granular coated web,

illustrated in Figure- 1, is contrasted with that shown in Figure 3, that the granules positioned fiatwise. as shown in Figure 1, cannot cut as rapidly or as eiiiclently as the angularly positioned grains-shown in Figures 2 and 3. The

, grains, as illustrated by Figure 3, are so positioned that they can penetrate the material 6 undergoing abrasion, whereas those positioned as in Figure 1 can only drag over the surface of the material and any penetration that does occur is due to small'sharp projections from the granules themselves or is due to the pressure applied to the backing or web P by the member I during the grinding operation. I

The diagrammatic or schematic drawin Figure 4, illustrates one form of apparatus suitable for carrying out our invention. ,In this draw-.

ing the web P is threaded over the roll II and in contact with the idler rolls l2 and I3 to the pressure roll I 6 and the adhesive roll I I. The adhesive roll 11 dips into liquid adhesive, contained in the adhesive tank I8, and by its rotation, applies a-layer of adhesive to the web. The adhesively coated web is then passedpartially around the adjustable guiding roll 20 and in contact with the adjustable idler roll 2| to another adjustable guiding roll 22, the contact with each of these rolls being on the uncoated side of the web. Thus, the adhesive coated web is positioned with the adhesive side downward. Lo-

cated beneath the adhesive coated web and in a position prior to the point at which the adhesive acquires an appreciable set, is the grain projecting means B. Y j

The grain projecting means B consists essentially of an endless belt 24 of such material as fine mesh-screen held in a horizontal position by means of the pulleys 25 and 26. A grain hopper 21 with an adjustable gate 28 anda dispensing roll 29i-is positioned to deliver granular material to the upper side of the endless belt 24, which in turn is driven by suitable means, not shown, to cause the granular material deposited thereon to be carried beneath the web P. Lo-

cated beneath the upper. surface of the belt 24 are positioned one or more air nozzles 31. .These nozzles are of a length as great as the-width ofthe-beltand haveadjustably slotted openings adapted to deliver a curtain of airat a high velocitygand of small volume surface of the belt. The adjustable feature of the-opening and obviously, the pressure applied to thenoz'zlescan be varied, whereby an air cur-f tain oi the desired character can be obtained.

The function of these air nozzles is to raise the grains from the belt, orient them, and project them onto the adhesive coated surface of the web. Granules which do not adhere to the adhesive surface fall back to the belt and are carried into the bin 34. If desired, or when it is found that the air has a tendency to chill or dry the adhesive, warm, humid air can be used.

Provision for causing the adhesive to acquire at least a preliminary set after the granules have been deposited on the web is made by incorporating a blower 33 capable of delivering a largevolume of air at a low pressure to the adhesive and granular coated web. This blower is located between the projecting means and the idlerroll 22 in order that the direction taken by the coated web does not change until the adhesive has acquired sufllcient firmness to prevent the granules from being positioned in any other manner than that desired.

From the adjustable supporting roll 22, the

coated web is drawn over the suction drums 35 and 36 and roll 40 to a suitable drying chamher. This drying chamber comprises a rack 4| for supporting the web P, and an endless conveyor 42 for transporting loops of the web to the rack 48.

With .certainclasses of granular particles, and particularly with very flne material, such as 200 mesh, we prefer to use a dense or closely woven conveyor belt to transport the granules and to position the air blast projector at the end of the belt directly under the adhesively coated web, as fllustrated in Figure 5. This drawing shows an adhesive coated web P positioned above a conveyor belt 6|. The conveyor belt 6| is supported by the pulleys 62, 63, 64, and positioned to receive granular material from a hopper 21 and to carry the granular material and discharge it above an air nozzle 65, which directs a stream of air through a screen 66. Means for causing the adhesive to acquire a preliminary set are indicated by the blower 33 and the break 61. Thus the granules are carried to the end of the belt and into a diflused curtain of high velocity air where they are projected upward onto said adhesive surface. The operation is very similar to that described inconnection with Figure 4, with the exception that the stream of air does not flow thr'oughthe conveyor belt.

Figure fiillustrates one modiflcati'onof apparatus suitable for projecting the granular material upwardly to the adhesive coated web in accordance with our invention. The apparatus 11- lustrated in Figure 6 comprisesan endless belt 45 of such material as canvas or the like, positioned horizontally on pulleys 41, 4 8 and 44, and a grain hopper 2'| wlth an adjustable gate 28, a dispensing roll 29, positioned to deliver granular material to the upper side of the endless belt 45. Driving means, which are not shown-in the drawings, are provided to move the belt in the direction indicated by the arrows on the pulleys 41 and 48. Located beneath the upper surface of the belt 45 are one or more heaters 48 mounted on the vertically adjustable supporting mem-- ber 50. These heaters are rotatable at speeds as desired and-so positioned with respect to the upper surface of the belt that-they deliver quick, sharp blows to theunder side of the-belt, when they are rotated. The striking of these beaters against the under side of the belt causes the gran"- ules carried by the belt to be projected upwardly,

and because of their upward projection through space, a substantial proportion of the grains become oriented with their major axes parallel to their lines of flight. The relative positions of the adhesive coated web and the grain. carrying belt 45 are such that the upwardly projected granules strikethe adhesive surface endwise and adhere to that surface in the same positions as they strike. Thus, if the web is held in a horizontal position and the granules are projected vertically upward, a substantial proportion of granules become positioned on the adhesive coated web in such manner that their axes are normal to the surface of the web. If, on the other hand, the web is not positioned horizontally, or if the grains are not projected vertically upward, the result is oblique positioning of the grainswith respect to the web. The coated side of the web' being downward, gravity tends to bring all of the particles into the same relationship with the web.

The modification of projecting means shown in Figure '7 comprises a rotatabledrum 5| having radially projecting arms 52 in an enclosure 53. Granular'materials are dispensed from a hopper 21 with an adjustable gate 28 and a dispensing roll 29 into the enclosure 53, and are thrown upwardly by the movement of the arms 52 on the drum 5|. By rapidly revolving the drum 5i, it is possible to impart suflicient velocity to the particles to cause them to align themselves with their major axes parallel to the direction in which they are traveling. A baflle 54 restricts the flight of the projected, particles to a desired direction. As in the case with the apparatus described hereinabove, it is possible to produce granular coated webs in which a substantial proportion of the particles are arranged with their major axes at an oblique angle to the web, or with their major axes normalto the web, by so positioning the web and the projecting means that the net result grit sizes.

The projecting means shown in Figure 8 comprise a grain feed hopper 21 positioned to discharge granular material onto and through distributingscreens H, and a plurality of air nozzles 13 arranged to discharge high velocity air through a diffuser screen [4 and toward an adhesive coated web P. Thus, the granules pass ticles are projected face by means of a'diifused current of air prothrough thescreens II and drop between the web P and the screen 14. As they fall, the paronto the adhesive surface of the web P.

There are many advantages gained .by projecting the granular material onto am adhesive sur= duced by apparatus of the character illustrated in Figures 4, 5 and'8'. It is to be understood, of course-that these drawings are for illustrative purposes and are not intended to limit-the scope of the invention to the use of the 'specifleappae ratus showriJj x j One advantage gained by the .useb'fdiffused air as theproj'ecting force by means of which the granular material is deposited an adsectional area of the air current, as by the use of more or less air nozzles, without reducing the velocity of the air. v

Another advantage gained by the use of an air current for projecting the granular material onto an adhesive surface of a web is that the particles can be oriented with their longer axes normal to the web. This is especially the case when the grains are projected upwardly to the adhesive surface, because the grains then hang downwardly from the web and are kept in their oriented positions by the action of gravity.

We have found that the granular particles penetrate the surface of the adhesive layer less readily when the viscosity of said adhesive is increased and, in order to produce a granular coating of predetermined or -standard" weight, we have found it necessary to increase the velocity'of the projected granules proportionately to the increase in viscosity of the adhesive.

In order to control and regulate the weight of the applied granular coatings, regardless of the viscosity of the adhesive or the size of the granules, we have provided in our apparatus means for varying the initial velocity of the projected particles. Referring again to Figure 4 of the accompanying drawings, the velocity at which the granular particles are projected from -the mesh conveyor belt 24 may be varied to any desired degree by increasing or decreasing the pressure and hence the nozzle velocity of the curtain of air issuing from the nozzles 3|. Obviously, the velocity of the projected granules is proportional to the velocity of the air stream.

In the modified form of grain applying device shown in Figure 6, the velocity at which thegranules are projected from the conveyor belt 65 may be controlled and adjusted to any desired degree by changes in the amplitude of the oscillations of the conveyor belt. Such adjustment may be effected by means of the adjustable member 50, supporting the rotatable beaters, whereby the projecting portion of the heaters 49 can be made to raise the conveyor belt to a greater or less degree during each half revolution.

With the type of grain applying device illustrated in Figure 7, the initial velocity of the granules projected by the drum may be controlled to any desired degree by varying the speed of rotation of said drum. For example, increasing the speed of rotation of the drum projector 5! increases the velocity of the granules projected upward onto the underside of the web P, and thus increases the penetration of the granules into the adhesive surface.

It will be seen from the foregoing disclosure that the practice of our invention results in the production of a superior granular coated web. By projecting the grains upwardly to a web with its adhesive coatedface positioned downward to catch the upwardlylprojected grains, 9. surface results that is sharper. The grains are so posi tioned on the web that they are better adapted to penetrate the material being abraded and to do Q with an expenditure of less work than has been required with the usual abrasive paper or cloth.

We have found from actual tests that a serrated surface produced in accordance with our invention sometimes lasts twice as long, and usually from 50 per cent to 100 per cent longer in actual operation, than the ordinary coated webs, I

and that the abrading or cutting rate is from two to three times as fast as that obtained with theusual coated webs While we have described our invention with specific illustrations, it is not intended that these illustrations shall define the scope of our invention. Variousmodifications may be made by those skilled in the art without departing from the spirit or scope of our invention as defined in the appended claims.

We claim:

,1. The method of manufacturing abrasivemoving web, means for moving said adhesively coated 'web into a position with the adhesive coated side facing downwardly, a feed belt for conveying abrasive particles into a position beneath said web, .a stationary support of mesh material for receiving and supporting said abrasi-ve particles beneath said web and a nozzle on the side of the stationary support opposite the side supporting-the abrasive particles for direct- "ing a blast of'gas through said mesh support to blow the abrasive particles against the adhesive coating. of the web material.

3. The method of manufacturing abrasive coated webs which comprises applying a base particles to a'rne'sh conveyor belt positioned becoating of liquid, adhesive to a moving web,

porting said adhesive coated web with anadhesive coated si e downward, supplying abrasive neath said web, and projecting said particles from said conveyor belt by means of air blown through said conveyor belt, said airbeing warmed and-humidified to prevent premature setting of the adhesive.

4. Apparatus for the manufacture of granular coated webs comprising means for supporting an adhesive coated web with an adhesive surface downward, means for conveying elongated granular particles into a position beneath said web, means for projecting said particles upwardly from said conveying means and orienting the elongated particles with their major axis at a substantial angle to said adhesive coated surface, and means for blowing a dessicating medium against said adhesive while-the web is in a downwardly facing position. v

5. The method of manufacturing abrasive coated webs which comprisesapplying a coating of liquid adhesive to a moving web, moving said adhesive coated web into a position with anadhesive coatedside'downward, projecting elongated abrasive particles upwardly into engagement with said adhesive coated web and orienting the elongated particles with their major axes at .a substantial angle to said adhesive surface and applying an air blast to the abrasive coatedweb prior to changing its direction of movement in order to set the adhesive while the web is still positioned with its adhesive coated side downward whereby the orientation of the abrasive particles is maintained during subsequent movement of said web.

6. Apparatus for the manufacture of abrasive coated webs comprising means for applying a base coating of liquid adhesive to a moving web, means for moving said adhesively coated web intoa position with the adhesive coated side facing downwardly, a feed belt for conveying abrasive particles into a position beneath said web,

a screen for receivingandsupporting said abrasive particles beneath said web and air blast means for projecting said abrasive particles upwardly from said screen into engagement with the adhesive coated surface of the web.

ROMIE L. MELTON. RAYMOND C. BENNER. HENRY P. KIRCHNER. 

